HEAT DISTRIBUTION TESTS

Prerequisite to sterilization or pasteurization.

Prerequisite prior to using a retort, or an oven, or a bath

A retort, an oven or a bath should be designed such that every containers receive the same thermal process

HOWEVER, before using a retort, an oven or a bath to process food products, heat distribution tests should be undertaken by a specialist in that field so as to verify the efficacy of both the design and the hook-up of the equipment.

How do we go about achieving heat distribution tests ?

The procedure goes as follows:

Load the retort/oven/bath with filled containers (filled with water or actual product, or a product substitute (a clay or bentonite suspension for example)
As the retort/oven/bath is being loaded, spread thermocouples or wireless loggers at several locations throughout the load

Once the heat is on

The procedure goes as follows:

  • Temperature is recorded regularly by every thermocouple or wireless loggers
  • So as to ensure temperature uniformity in every point of the load.

Objective of the test

The temperature must be uniform throughout the load within one minute after process is started.

Who performs those tests?

A thermal process specialist

Pharmaceutical Industry

The requirements presented here for the food industry apply just as well to the pharmaceutical industry.

in a vertical retort and a horizontal retort

Sensors location

Normally, the temperature sensors will be located outside the containers, in between each others.

Steam retort

Steam retorts are a special case since they contain lots of air when the door or lid of the retort is closed. And we know that air is a good insulator.

IF THE THERMAL PROCESS IS TO TAKE PLACE IN A STEAM ONLY ENVIRONMENT, THE AIR MUST BE RID OF.

The vent cycle is in fact designed to evacuate the air from the retort.

How long should the vent last

The answer lies in the heat distribution test.

EACH SYSTEM WILL HAVE ITS OWN VENT CYCLE.

More broadly, heat distribution tests are required :

  1. To develop or validate a vent procedure;
  2. To determine whether there is a cold or slow heating zone in the retort;
  3. For any new installations;
  4. Whenever a modification is made in the processing area that could affect the heat distribution

To summarize

Heat distribution tests are a prerequisite to sterilizing or pasteurizing a food product in a retort (or oven, or bath, etc).

Heat distribution tests enable the thermal process specialist to set-up operating procedures so as to guide the user

These operating procedures must be followed by the operator for every batch.

Tests performed on several types of retorts

Developex has performed tests on several types of retorts

Allpax immersion and Stock immersion

 

Lubeca immersion and Barriquand, water cascading
 

or a steam-air Lagarde

Crateless steam retort, Malo

Steam only FMC continuous cooker, Sterilmatic

Paramètres de ventilation et de mise en route de l’autoclave

Une fois les paramètres de ventilation et de mise en route de l’autoclave,
Ils doivent être maintenus tels quels à moins d’être revus par un spécialiste en procédés thermiques.

Que l’autoclave soit plein ou rempli partiellement, le même cycle de mise en route doit toujours s’appliquer.

Qu’est-ce qui justifie de reprendre ces tests?

  • Lorsqu’on introduit un format plus petit
  • Lorsqu’on introduit un produit rempli froid
  • Lorsqu’on passe d’un chargement d’autoclave pêle-mêle à un chargement avec intercalaires